Stain inhibitor in photographic paper bases

ABSTRACT

PHOTOGRAPHIC ELEMENTS HAVING POLYOLEFIN COATED PAPER SUPPORTS, PROVIDED WITH SILVER HALIDE EMULSION LAYERS CONTAINING SILVER HALIDE DEVELOPING AGENTS, WITH OR WITHOUT HYDROPHILIC BACKING LAYERS, EXHIBIT STAIN DUE TO MIGRATION OF THE DEVELOPING AGENT TO PAPER AND TO THE BACKING LAYER. STAIN IS AVOIDED BY SIZING THE PAPER WITH AN ALDEHYDE BISULFITE AND COATING ANY BACKING LAYER AT A PH LESS THEN 7 PREFERABLY ABOUT 3 TO 4.

United States Patent Oflice 3,671,248 Patented June 20, 1972 3,671,248STAIN INHIBITOR IN PHOTOGRAPHI PAPER BASES Merle K. Eldridge and Roy C.Bloom, Hilton, and Douglas C. *Joseph, Victor, ,N.Y., assignors toEastman Kodak Company, Rochester, N.Y.

Filed June 10, 1970, Ser. No. 44,965 Int. Cl. G03c 1/48, N86

US. Cl. 96-76 R 7 Claims ABSTRACT or THE DISCLOSURE v This inventionrelates to light-sensitive photographic elements and more particularlyto, a process for preventing discoloration thereof due to migration ofdeveloping agent from an emulsion layer to the support.

An element of particular use in photography comprises a polymer coatedpaper support provided with a silver halide emulsion layer andcontiguous silver halide developing agent such as a polyhydric phenol,e.g. hydroquinone. It is observed that after storage of this paper,stain is visible particularly when viewing this paper from the sideopposite the emulsion layer. We have unexpectedly discovered that thisstain arises, during storage, from gradual migration of the developingagent from the emulsion through the relatively impervious underlyingpolymer layer to the paper fiber where it is oxidized to produce theobserved stain.

Another element of use in photography comprises-a polymer coated papersupport having a hydrophilic organic colloid backing layer, suchas anantistatic backing, on one surface and on the other surface a silverhalide emulsion layer and contiguous silver halide developing agent suchas hydroquinone. It has been found that immediately after coating anddrying the emulsion layer on the support and winding in a roll,particularly when the emulsion layer contains the developing agent or itis in a layer on the emulsion surface, a pronounced brown stain at onceappears in the organic colloid backing layer. We have discovered thatthis fresh stain arises from migration of the developing agent to theadjacent polymer surface when the paper is wound in the roll. Inaddition, more stain arises upon storage of the paper due to thementioned migration of developing agent from the emulsion through therelatively impervious underlying polymer layer to the paper fiber.

In a further aspect of our invention we have discovered that this brownstain does not appear on fresh or aged polymer coated paper if the paperstock has been treated, for example coated or tub sized, with acomposition containing a lower-aldehyde bisulfide so as to obtain atleast about 30 milligrams per square foot. However, if the hydrophilicbacking layer is present, it must be acidic having a pH less than 7 andpreferably about 3 to 4, otherwise the stain still appears.

The accompanying drawing shows in greatly enlarged cross-sectional viewsrepresentative photographic elements of our invention wherein in FIG. 1layer 10 is ordinary photographic paper base sized with an aldehydebisulfite and carrying extruded polyethylene layers 11 and emulsionlayer 13 containing developing agent. No

stain arises on winding the paper in a roll or on ageing the paper. Inthe FIG. 2 element an antistatic layer of low pH is provided to avoidstain.

The polymer coated paper used in production of the sensitivephotographic elements as illustrated in the drawing can be prepared byfirst tub sizing a photographic paper base of about 30 pounds perthousand square feet with an aqueous composition containing the aldehydebisulfite, followed by coating or extruding polymer layers, e.g.polyester, polyolefin and the like, preferably a polyolefin layer, ontoboth surfaces of the paper. These polymers include polyolefins such aspolyethylenes and polypropylenes and ethylene-propylene copolymers,polystyrene, polybutenes, polypentenes, polyacrylic acid esters, linearpolyesters such as polyethylene terephthalates, polycarbonates,polyamides such as nylon, cellulolose esters, polyacrylonitrile,polyvinylidene chloride and other copolymers of the indicated monomerssuch as ethylenevinylacetate copolymers.

The paper can first be treated with corona discharge as described in US.Pat. 3,411,908 to facilitate adhesion of the polymer layers to thepaper. About 8 pounds of polyethylene per thousand square foot of papersurface is useful for this purpose. When this polymer coated paper(FIG. 1) is activated, especially with controlled speed and coronafrequency as disclosed in Ambusk, US. patent application Ser. No.724,491, filed Apr. 26, 1968, now Pat. No. 3,549,406 and coated with theemulsion containing developing agent, no stain appears after winding inthe roll or on storage of the paper. In another case (FIG. 2) when thepolyethylene paper is coated at pH less than 7 with a hydrophilicorganic colloid backing layer 12 such as gelatin, or a water-solublecellulose ether or a cellulose ester, starch, etc., optionallycontaining an ionic antistatic agent, after emulsion coating of thispaper stain is not visible after winding the paper in a roll even withthe emulsion and antistatic layers in contact in the roll or on ageingthe paper. A useful ionic antistatic composition includes an alkalimetal salt of an alkylaryl polyether sulfonate or of a polymericcarboxylic acid, or a mixture thereof. In some cases it may be desirableto incorporate colloidal silica into the antistatic composition toobtain the desired antistatic properties. The above sulfonates aredescribed in detail in US. Pat. 2,600,831, for example, the salt soldunder the trade name of Triton X200 (p-[1,l,3,3tetramethylbutyl]phenoxyethoxyethyl sodium sulfonate) sold by Du Pont deNemours and Company. The polymeric carboxylic acids are illustrated bypolymerized acrylic acids such as polyacrylic acid, polymethacrylicacid, and polyethacrylic acid such as Daxad 30 (trade name for thesodium salt of polymethacrylic acid) sold by Dewey and Almy ChemicalCompany. Many other alkali metal salts of polymeric carboxylic acids mayalso be utilized as the ionic organic antistatic agent, for example,potassium polyacrylatcs, alkali metal salts of acrylic acidmethylacrylate copolymer, and the like. In addition, the sodium salt ofcellulose sulfate can be used alone for the antistatic layer. A gelatinlayer may separate layers 11 and 12 for controlling curl.

Useful developing agents for the emulsion layer include the polyhydricphenol silver halide developing agents such as hydroquinone, substitutedhydroquinone, e.g. chlorohydroquinone, aminophenols, 3-pyrazolidones,catechol, substituted catechols, reductones, hydrazines andhydroxylamines. Mixtures of these developing agents are especiallyuseful such as a mixture of hydroquinone and a 3-pyrazolidone, e.g. 50to 200 milligrams hydroquinone per square foot and 0-20 miligrams1-phenyl-3-pyrazolidone per square foot. If desired, the developed agentcan also be made contiguous to the silver halide of the emulsion layerby being coated either in a subbing layer under the emulsion layer or ina layer.

The silver halide emulsions useful with this invention can comprisesilver chloride, silver bromide, silver bromoiodide, silverchlorobromiodide or-mixtures thereof. The emulsions may be coarse orfine grained and can be prepared by any of the well-known procedures.Surface image emulsions or internal image emulsions may be used ifdesired. Regular grained emulsions may be used. The silver halideemulsion .grainsmay, in a particular coating, vary widely in grain sizeor mono-dispersed emulsions may be used. The emulsion used may comprisegrains which have irregular crystal structures or they may be regulargrained emulsions such as cubic gained emulsions. Negative typeemulsions may be used or, if desired, direct positive emulsions may beused in the practice of the invention. The following examples will serveto illustrate the invention.

EXAMPLE 1 A photographic papersupport of about 30 pounds per thousandsquare foot is tub sized with the following compositions:

*Sodium formaldehyde bisulfite.

The sizing operations A, B and C yield coverages of about 125milligrams, 62.5 milligrams and 3l.2 milligrams of the aldehydebisulfite per square foot, respectively. At least about 30 milligramsper square foot is useful to produce the advantageous results mentionedbelow.

Thereafter, polyethylene is extruded onto the corona activated surfacesof the papers A, B, C and D at about 8 pounds per thousand square feet.The wireside of the polyethylene paper is then coronaactivated andcoated with the following aqueous acidic antistatic composition,applying approximately 3 grarns/m. (dry weight).

Parts by wt. Starch 5.0 Daxad 30 5.0 Triton X200E 0.2 Water 85.9

Butyl alcohol pH 3.5 (adjusted with hydrochloric 4 acid) 4.0 The faceside of the polyethylene coated paper is corona activated and coatedwith a gelatin-silver chlorobromoiodide emulsion containing hydroquinoneand 1- phenyl-S-pyrazolidone so as to obtain about :125 milligramshydroquinone and 6 milligrams 1-phenyl-3- pyrazolidone per square foot.It is observed that just after preparation of papers A, B, C and D asdescribed above and winding in the roll, papers A, B and C viewed fromthe surface opposite the emulsion layer had high reflectivities (about80% reflectance of light of wavelength 460 mm.) whereas thecorresponding surface of paper D not containing SFB showed a pronouncedbrown stain (reflectance about 55% of 460 mm. light). Additional stainappears on D after storage. The papers A, B, ,C and D have structuresessentially as shown in FIG. 2 of the aclayer. on top oftheemulsion.

companying-drawing is.-..t-he-..case. .of paper. D. thev stain. beingvisible on viewing from the side opposite layer 13.

Papers A, B, C and D are exposed to black-and-white images and processedby use of an alkaline activator solution to initiate silver halidedevelopment followed by fixing and washing. As a result; papers-A", Band showed no stain in the highlights of the images or on the rearsurface wh'ereas some stain is still visible-on the'correspondingsurfaces of paper D not containing the SFB.

' EXAMPLE -2 The processes of Examples 1A and are carried out exceptomitting the antistatic layer (FIG. 1). As a result,

followed by extrusion or solvent coating ofpolymer layers on each papersurface. If desired, White pigment can be incorporated into the polymerlayer under the emulsion layer. The polyethylene layers can be replacedwith other polymeric layers including cellulose ester and linearpolyesters. Similarly, other antistatic agents and hydrophilic.

organic colloid carriers may comprise the acidic backing layer.

The invention has been described in detail with particular reference topreferred embodiments thereof, but it will be understood that variationsand modifications can be effected within the spirit and scope of theinvention.

What we claim is:

1. A light-sensitive photographic element comprising a paper supporttreated with a lower aldehyde bisulfite, eX-' truded polymer layers oneach surface 'of the paper,-a silver halide emulsion layer andcontiguous silver halide developing agent adhered to thesurface of oneof the polymer layers, and a hydrophilic organic colloid layer having a.pH less'than 7 adhered to the surface of the other polymer layer.-

2. The element according to claim 1 wherein'the polymer layers contain-apolyolefin or olefin copolymer.

3. The element according to claim 1 wherein the aldehyde bisulfite issodium formaldehyde bisulfite and the veloping agent is hydroquinone.

developing agent'is a polyhydric phenol contained in the emulsion layer.4. The element according to claim 1 wherein the hydro.-

philic organic colloid layer is an antistatic layer contain-.- a ing analkali metal salt of an alkylaryl polyether sulfonate' or of a polymericcarboxylic acid, or a mixture thereof.

5. The element according to claim 1 wherein the developing agent is apolyhydric phenol.

6. The element according to claim '1 7. The element according to claim 1wherein the developing agent is a mixture of hydroquinone and a 3--pyrazolidone.

' a References Cited UNITED STATES'PATENTS 3,212,895

wherein the de-

